In industrial mixing applications, it has been known to use vessels having a driven shaft entering through an opening in the top of the vessel to drive an impeller in the vessel attached to the lower parts of the driven shaft. In some applications, the top of the mixer shaft terminates in a flange connection. A drive assembly including a motor has a drive shaft connected via flanges to the mixer shaft.
Where the mixer shaft enters through the top wall of the vessel, it has been known to provide an assembly that includes a sealing ring around the mixer shaft that prevents material inside the vessel from escaping around the entrance area of the mixer shaft. It has also been known in such as assembly to provide a single ball bearing support ring generally near the sealing ring and above the sealing ring that reacts to radial and axial loads on the shaft, and thus fixes the shaft radially and axially at the point of location of the ball bearing ring.
A disadvantage of one known arrangement is that the employment of a single ball bearing support in some instances does not fully handle the various types of reaction loads that may be present in the shaft. For example, mixing shafts are often subjected to various tilting and bending loads along various points of the mixer shaft length. If these loads are not properly accommodated for, undesirable angular bending or misalignment may occur below the single ball bearing ring, in the vicinity near the seal ring, hindering the effectiveness and/or life of the sealing ring. Moreover, bending may also occur above the single ball bearing ring, at the top of the mixing shaft, thus transmitting undesirable bending and/or loads to the drive shaft coupled thereto.
In view of the foregoing, there is a need in the art for an improved seal and bearing assembly and method that can react to bending loads and/or provide improved radial and axial load handling capability.